Corrosion inhibiting composition



frequently these Patented Sept. 20, 1949 CORROSION INHIBI'I'ING COMPOSITION Knapel F. Schiermeier, Alton, and Walter E.

Heinz,

Roxana, Ill., assignors to Shell Development Company, San Francisco, Calif., a corporation of Delaware No Drawing. Application March 13, 1945,

Serial No.

19 Claims. (Cl. 25243.4)

This invention relates to new and improved corrosion preventive oils and greases. It particularly pertains to solution-stable mineral oil compositions containing dissolved amounts of certain organic polyhydric alcohols which provide an unusual degree of protection against corrosion to ferrous metals and also against corrosion of other metals and alloys such as copper, brass, bronze, I

zinc, cadmium, aluminum, magnesium, etc.

It has been found that certain partially esterified polyhydric alcohols wherein the ratio of free hydroxyl to ester radicals is at least 1:1, and preferably greater than 1:1 exhibit anti-corrosive properties when applied to metallic surfaces in solution of hydrocarbon oils. However, this discovery by itself is of little practical value since compounds have very limited solubilities in hydrocarbons, particularly at relatively low temperatures at which rustprooflng oils may have to glyceryl mono oleate in a refined mineral oil at 75 F. is about at 70 F. about .1%, and at 50 F. immeasurably small. To enable the dissolution of effective amoun mutual solvents are required. l I

A considerable number and variety of substances have been evaluated as mutual solvents in attempts to overcome this difnculty but have been found unsatisfactory for one or more reasons. Thus, the addition of amines does not produce satisfactory solution stability and frequently decreases the oxidation stability of the organic medium, oil-soluble alcohols decrease the corrosion protection in addition to yielding unstable solutions, oleic acid and other normally liquid fatty acids increase the Solubility of the dihydroxyalcohols in mineral oil but greatly reduce their rust inhibiting potency, etc.

1 It has been discovered, however, that this problem may be solved in a highly satistactory manner by the employment of salts, in particular the ammonia, alkali and alkali earth metal salts of oil-soluble organic sulfonic acids. Certain oilsoluble sulfonic acids are known as mahogany acids as distinguished from green acids or watersoluble sulfonic acids and are most readily obtained as a by-product from the treatment of petroleum (for example, lubricating oil fractions) with sulfuric acid. However, oil-soluble sulfonic acids may also be'obtained from the treatment of many other organic compositions such as alkyl benzenes, alkyl naphthalenes, coal tars, etc. with concentrated sulfuric acid, or by treatment of aliphatic or cycloaliphatic compounds such as C10 and higher hydrocarbons with chlor sulfonic acid, 55'

be used. Thus, the solubility of inhibitors and Oil-soluble sulfonates oi dicarboxylic acid esters such as malonic acid esters represent still another pe.

While many of these organic sulfonates have some discernible corrosion inhibiting properties themselves, they are in many ways greatly inferlor to the present polyhydric alcohols as rust are employed in the present application for the chief purpose of maintaining a homogeneous solution of the alcohol in petroleum derived vehicles. Indeed, particularly if used in relatively high concentrations such as are normally required for them to exert their anti-corrosive effect, c. g. about 3% or more, they actually decrease the anti-corrosive effect which would be obtained from the alcohols by themselves if the latter were sufficiently soluble. Consequently, only the amount of sulfonates should be employed which is actually necessary to hold the ester a1- cohols in solution at the lowest temperature to which the composition will be exposed during storage, transportation or use. Often, a solution which will remain homogeneous at normal room temperature (-70" F.) is suflicient. In other instances, solution stability at a freezing temperature (32 F.) and lower is desirable.

One reason for the harmful efiect of excessive amounts of the sulfonate probably lies in the mechanism of the corrosion inhibition by ester alcohols. This mechanism apparently involves plating out of the alcohol from its solution on thev metal surface. The closer the solution is to its saturation point with respect to the ester a1- cohol, the more easily is the latter plated out. For this reason, the esteralcohol must be only little soluble in the hydrocarbon medium, and in general best results are obtained with ester alcohols whose solubility at normal room temperature in hydrocarbon oils is below that of effective inhibiting concentrations, so. that at least a small amount of mutual solvent is required to produce Preferably at least one hydroxyl radical is on a terminal carbon atom but it may be removed from h minal carbon atom by as many as three fined mineral oil which is employed will of course fa r fofi atoms. Additional OH radicals may be vary with the specific application. I! it is delocated near the first two hydroxyl groups. To sired to produce a rust-inhibiting lubricant for this alcoholic portion of the molecule there is atan internal combustion engine the present addiominantl hydroc r n p i n c ntives will be incorporated in a lubricating oil 221m r i mnber of Zarbon atoms sufllcient to which otherwise meets the requirements, such as give the molecule a total minimum carbon conviscosity, viscosity index, pour point, volatility, tent of about 12 "and preferably about 15 to 46 color, etc., for this use. On the other hand, if rbon atoms, This hydrocarbon portion is ata general utility or instrument oil is required, the tached to the alcoholic portion of the molecule additives will be added to an oil of lower viscosity through an ester linkage which may be formed as the case may require, for example having a between the hydroxy or an acid radical (if there viscosity at 100 F. of 10-25 cs. The composiis one) of the polymdric alcohol on the one hand, tions of this invention may be applied to metal and an acid or alcohol respectively on the other. surfaces by rolling, dipping, brushing, spraying, It is desirable that the hydroxyl'radicals and ester swabbing, troweliing, etc. linkages of the ester alcohol be as close together A number of specific embodiments of the inas possible, at least two hydroxyl radicals bein vention follow: separated from each other by not more than three Example I directly connected atoms and preferably being attached to -vicinal carbon atoms. It is advan- 29 A general preservative lubricant meeting the tageous if the several polar groups are attached lfiqlllrements of A y Ordnance sh d-fleato directly connected carbon atoms. tion AXS- 6'74 .(Rev. 2) was made by-addmg to a It will be seen that the ester alcohols may be refined i l l bricating oil or API gr i y derivatives of glyceflne erythritol, penta erythriand 740 S. U. S. viscosity at 100 F., 4.5% w. of

tol, mannitoL'sorbitol, sorbitan, etc. The acid ly erol m no oleate. and 0.5% w. of a 50% conthe case ma be) foming t ester centrate of sodium salt of mahogany acids. This ,fi fi' ggs gaf g, should have t; composition afforded protection to a steel strip about 10, and preferably between about 10 and 40, for 400 hours in the humidity cabinet t 100 carbon atoms, in the tong1 6:5 an aliph 1 g z r ti ra clusdllliltgalfll igfigfzcgznpflse or example capryl, A coating composition for hot application to decyl (decanyl), cetronellyl, undecyl, undecylmetal parts was compounded from 6 em, 1a ury] (dodecyl) "may! myristyl (tetra 120 penetration aromatic petroleum extract,

46% w. short residue petrolatum, 5% w. neutral, decyl) g 'g i high V. I. lubricating oil, 2.7% w. glycerol mono gqg m i lg 232% ga :535: oleate and 0.3% w. of a 50% concentrate of e 1 y r y in 1 7 sodium salt of mahogany acids. It had a melting such as are contained in the acids ob a ed rom int of 146 F and gave protection m the resin or tall 011 as well as in naphthenic (i. e.

m ms um humidity cabinet for over 1000 hours. If desired, cycloanphatic) acids having 8 req e n this composition may be diluted with mineral ber of carbon atoms are also applicable. 40

The acid which may form the ester with the spirits or naphtha and applied to the metal at polyhydric alcohol is preferabl a carboxylic acid, rg dipping brushing or although sulfonic, alkyid sulfurlic, phfflphoric, p Example alkyl phosphoric, etc. ac ds are a so use Adequate corrosion inhibiting quantities of the 5 To a solvent-extracted light spray oil was added present ester alcohol are on the order of from 1.5% w. glycerol mono oleate, 2% w. commercial about 0.5% or prgigrably 1gb w.tup to about 5% pour depressor, 082% w. ditrlarllary butyl 2231;. or 10% w. depen g on t e na ure of he parcresol as ant -oxi ant, and o w. of a o ticular application. Usually a-concentration of concentrate of sodium salt of mahogany acids. about 2%-3% w.issatisfactory. By the designa- This met the requirements for a small arms tion 'w. is meant the per cent by weight of lubricant or U. S. Army Ordnance specification the additive based on the weight of the medium. MES-777, aflordlng humidity cabinet protection The amount of the sulionate used, depending at 100 F. for 200 hours. on its solubility in the particular petroleum Example w medium involvedt, the sohgiiity of the ester A t 1 hibm 1 t t u tin s alcoholin the pe roleum m um, and he solum5 n E 115 111111611 0 11189 g bility of the ester alcohol in the sulionate, may Government spe c i 0 a w p ep e vary from about 3 times to /20 and preferably by dissolving in an acid treated neutral distillate about 1%; times to /15' that of the ester alcohol. 1 ving a viscosity at 100 F. of about 8 Usually the solubility or these alcohols is greater so centistokes the following additives:

in relatively aromatic as well as more viscous Sorbitan mono steamte 13-15% petroleum fractions than in relatively paramnic sodium ulfo at (ommmblej 2.5% arid/01 lighter 0115- 2,6-ditertlary butyl-fi-methyl phenol Th hydroca bon, medium employ d to dispe se (oxidation inhibitor) 3% the ester alcohols is preferably a Pour and viscosity lmprover 3 0% it may be a solid or plastic such as paraflln, v petroleum or soap-thickened grease. It is de Example v sirable that asphaltenes or resinous constituents The harmful effect oi excessive amounts of of crude petroleum be absent, since they may the sulfonate is well demonstrated by the followinterfere with the rust protection of the ester ing comparisons: Two solutions of 3% sorbitan alcohols; hence the media comprise generally remono stearate in a light lubricating oil were "fined mineral oil or fractions thereof. Refining prepared, one containing '/z% and the other 3% may be by percolation, suliuric acid treatment, oil-soluble sodium sulfonate. Steel panels coated extraction with selective solvents, propane prewith these oils had lives of 750 and 500 hours, cipitations, etc. The particular traction or rerespectively. Similar. solutions using sorbitan mono palmitate instead of the stearate gave lives 01 650 and 450 hours, respectively.

' The effect of high solubility of the alcohol ester is shown by the comparison below:

Two solutions in a light lubricatingv oil with 3% each of sorbitan trioleate and sorbitan monooleate were made. The former was completely soluble; The latter was incompletely soluble. The relative lives in the humidity cabinet of steel panels treated with the solution were 72 and 300 hours, respectively.

We claim as our invention:

6. A corrosion inhibiting composition comprising a major amount or a mineral oil and at least 0.5% and up to about by weight 1. A homogeneous, storage-stable solution in an essentially hydrocarbon medium of a corrosion-inhibiting amount 01' a partial ester of an acyclic polyhydric alcohol an aliphatic acid having from 10 to 40 carbon atoms, said partial ester having the following properties: a melting point below about 200 F., a solubility in said medium below that enabling dissolution of said amount at normal room temperature in the absence of a mutual solvent, a ratio of hydroxyl to ester radicals of at least 1:1, a content of at -.least 12'carbon atoms and of at least 2 hydroxyl radicals separated from each other by not more than 3 directly connected atoms, said solution additionally containing an oil-soluble salt of an organic sulfonic acid in an amount suflicient to maintain the ester in solution under normal storage conditions.

2. A homogeneous, storage-stable solution in an essentially hydrocarbon medium of a corrosion-inhibiting amount or a partial ester of an acyclic polyhydric alcohol an aliphatic acid having from 10 to 40carbon atoms, said partial ester having the following properties: a melting point below about 100 F., a solubility in said medium below that enabling dissolution of said amount at normal room temperature in the absence of a mutual solvent, 2. ratio of hydroxyl to ester radicals of at least 1:1, a content oi at least 12 carbon atoms and of at least 2 hydroxyl radicals separated from each other by not more than 3 directly connected atoms, saidsolution additionally containing an oil-soluble salt of an organic suli'onic acid in an amount sufllcient .to maintain the ester in solution at about 32 F.

3. A corrosion inhibiting composition comprising, as a carrier, a major amount of a mineral oil having dispersed therein at least 0.5% by weight of a partial ester of an acyclic polyhydric alcohol and an aliphatic acid having from 10 to 40 carbon atoms, said partial ester having at least two free hydroxy radicals separated from each other by not more than 3 directly connected atoms and having a melting point below about 200 F., said partial ester being solubilized in the mineral oil by addition thereto of an oilsoluble salt of petroleum sulfonic acid, varying in amounts of from about 1 /2 times to about he or the partial ester.

'4. A corrosion inhibiting composition comprising as a carrier 9. major amount of a hydrocarbon medium having dispersed therein at least 0.5% and up to about 10% by weight of a glycerol monoester and a minor amount suflicient to solubilize said glyceroyi monoester of an oil-soluble salt of petroleum sulfonic acid.

5. A corrosion inhibiting composition comprising a major amount of a mineral oil and at least 0.5% and up toabout 10% by weight (based on the mineral oil) of a glycerol monoester and an oil-soluble salt of petroleum sulfonic acid added in amounts of from 1% times to about /15 of the glycerol monoester.

(based on the mineral oil) of a glycerol monooleate and an oil-soluble salt of petroleum sulfonic acid added in amounts of from 1 times to about /15 ot the glycerol monooleate.

'7. A corrosion inhibiting composition comprising a major, amount of a mineral oil and at least 0.5% and unto-about 10% by weight (based on the mineral oil) of glycerolmono naphthenate and an oil-soluble salt of petroleum sulfonic acid added in amounts of from 1 /2 times to about /15 of the glycerol mono naphthenate.

8. A corrosion inhibiting composition comprising a major amount of a mineral oil and at least 0.5% and up to about 10% by weight (based on the mineral oil) of a glycerol monoester and an oil-soluble salt of petroleum sulfonic acid added in amounts of from 1 times to about /is of the glycerol monoester and a minor amount oi. an alkyl phenolic anti-oxidant.

9. A corrosion inhibiting composition comprising a major amount of a mineral oil and at least 0.5% and up to about 10% by weight (based on the mineral oil) of a glycerol monooleate and an oil-soluble salt of petroleum sulfonic acid added in amounts of from 1% times to about In or the glycerol monooleate and a. minor amount of an alkyl phenolic anti-oxidant 10. A homogeneous, storage stable solution in an essentially hydrocarbon medium 01' a corrosion inhibiting amount of a glycerol mono ester, the acid radical having 10 to 40 carbon atoms, said solution additionally containing an oil-soluble alkali metal salt of an organic suli'onic acid, in an amount suiilcient to maintain the ester in solution under normal storage conditions.

11. A homogeneous, storage stable solution in an essentially hydrocarbon medium of a corrosion inhibiting amount of a glycerol mono ester of a fatty acid having from 10 to 40 carbon atoms, said solution additionally containing an oilsoluble alkali metal salt of an organic sulfonic acid, in an amount suflicient to maintain the ester in solution under normal storage conditions.

12. A homogeneous, storage stable solution in an essentially hydrocarbon medium of a corrosion inhibiting amount of a glycerol mono-oleate, said solution additionally containing an oil-soluble alkali metal salt of an organic sulfonic acid, in an amount suflicient to maintain the ester in solution under normal storage conditions.

13. A homogeneous, storage stable solution in an essentially hydrocarbon medium of a corrosion inhibiting amount of-a glycerol mono naphthenate, said solution additionally containing an oil-soluble alkali metal salt of an organic sulfonic acid, in an amount suflicient to maintain the esterin solution under normal storage conditions.

14. A homogeneous, storage stable solution in an essentially hydrocarbon medium of' a corrosion inhibiting amount of a partial ester f an acyclic alcohol having from 3 to 6 carbon atoms and an aliphatic acid having from 10 to 40 carbon atoms in which each available carbon atom of said alcohol has one hydroxy group attached thereto, said solution additionally containing an oil-soluble alkali metal salt of an organic sultonic acid, in an amount suii'icient to maintain the ester in solution under normal storage conditions.

'15. A corrosion inhibiting mineral oil composition comprising a, major amount of mineral oil as a carrier, a minor amount, suflicient to sion inhibiting amount of a glycerol mono-oleate,

said solution additionally containing an oilsoluble alkaline earth metal salt of an organic sulfonic acid, in an amount sufllclent to maintain the ester in solution under normal storage conditions.

17. A homogeneous, storage stable solution in an essentially hydrocarbon medium 01 a corro-- sion inhibiting amount of a partial ester of an acyclic alcohol having from 3 to 6 carbon atoms. 20,

and an aliphatic acid having from 10 to 40 carbon atoms in which each available carbon atom of said alcohol has one hydroxy group attached thereto, said solution additionally containing an oil-soluble alkaline earth metal salt of an organic sulfonic acid, in an amount suilicient to maintain the ester in solution under normal storage conditions.

18. A homogeneous, storage stable solution in 8 anessentlaily hydrocarbon medium or a corrosion inhibiting amount oi a partial ester of an acyclic alcohol having-from 3 to 6 carbon atoms and an aliphatic acid having at least 10 carbon atoms, said solution additionally containing an oil-soluble sulionate in an amount suflicient to maintain the ester in solution under normal storage conditions.

I 19. A homogeneous, storage stable solution in an essentially hydrocarbon medium or a corrosion inhibiting amount of a partial ester of an acyclic polyhydi'ic alcohol. said solution additionally containing an oil-soluble sulfonate, in an amount sufllcient to maintain the ester in solution under normal storage conditions.

KNAPEL F. SCHIERIVIEIER. WALTER E. HEINZ.

REFERENCES crrnn The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 25 2,339,200 Sowa Jan. 11, 1944 2,345,199 Hodson Mar. 28, 1944 2,366,817 Towne Jan. 9, 1945 2,371,333 Johnston Mar. 13, 1945 2,398,193 Sharp Apr. 9,1946 

